Conventional bevel gear casings for track-type earth-moving vehicles are usually divided into three compartments by means of a pair of centrally disposed laterally spaced walls. The central compartment formed by such walls usually contains a bevel gear and a shaft therefor which has end portions extending axially through such walls into oppositely disposed outer compartments. Within the central compartment, the main bevel gear meshes with another bevel gear, conveniently referred to as a bevel pinion, which is driven by the vehicle transmission for imparting driving torque to the bevel gear shaft. The axially opposite ends of the bevel gear shaft are usually operatively connected to left and right track steering clutches and brakes which are individually disposed within the opposed outer compartments. Such steering clutches and brakes are, in turn, coupled to their respective final drives for driving the opositely disposed tracks of the vehicle.
Conventionally, a pair of tapered roller bearings are mounted individually within the laterally spaced central walls of the casing for rotatably supporting the opposite ends of the bevel gear shaft and for absorbing the usually high axial thrust loads caused by the natural tendency for the bevel gear and pinion to separate during meshing. Such separating is caused by a component of the driving force being transmitted between the bevel gear and pinion due to the pressure angle of such a force, as well known in the art. This separating force causes one or the other of the tapered roller bearings to run under high loading and for the oppositely disposed tapered roller bearing to run lightly loaded.
Such an imbalance in loading can cause deflection in the casing walls which could result in a premature failure of the bearing or wall components.
Some examples of the prior art bevel gear mounting arrangements are found in U.S. Pat. Nos. 1,033,102, 1,937,950, 3,194,083, 3,364,791, and 3,442,444 to Huff, Ford, Ballard, Truckle and Kievit respectively.